In China, emissions of pollutants, such as sulfur dioxide, nitrogen oxides and others in the iron and steel industry ranked the forefront of the industry. More than 50% of SO2 and NOx emitted in the iron and steel industry are from the sintering process. The “Emission standard of air pollutants for sintering and pelletizing of iron and steel industry” issued in 2012 puts forward higher requirements for the emissions of SO2 and NOx.
As seen from economic benefits and application prospects, it is the most practical significance that the purification technology can achieve combined removal of SO2 and NOx. As seen from enterprise researches and literature reports, the dry purification technology can achieve the purpose of combined removal. For example, the active coke desulfurization and denitration technology shows greater technical advantages, which produces no secondary pollution, and has received enough attention in recent years. But due to the performance of dry raw materials and excessive economic costs, the promotion thereof is subject to a certain constraint. There are a lot of reports of desulfurization and denitration purification technology, in which NO in flue gas is oxidized to NOx having a high valence, and then reacts with basic absorbent. During the contact process of flue gas and oxidant, SO2 will inevitably and partially be oxidized to SO3. However, SO3 cannot be effectively removed by wet removal process, resulting in the transformation of sulfur dioxide pollutant morphology, and the final removal cannot be achieved.
Relevant experts and scholars put forward semidry process combined removal method. From a technical point of view, the method for flue gas desulfurization by circulating fluidized bed semidry process has been quite mature. On the basis of that, it is a development trend at home and abroad to conduct technical upgrades and develop combined desulfurization and denitration technology.